Times Book Of Crosswords

[barnaclebill58]

Please parse these for me.
1.Ruminate about motorway replacing new green . Ans Immature (green). Motorway is m or mi and presumably that replaces n in a word meaning ruminate but can't get it.
2. Birds leaving middle of valley for crest. Ans cockscomb (crest). Cocks are birds but don't get how "leaving middle of valley" =comb.
3. Rugbyplayer with common name is laughing stock. Ans locksmith (second row plus common name smith). Have googled extensively but can't see how the laughing stock works.
4. Broadcast about fish and fowl using outdated term. Ans sparrow. No idea.
I do wish the book had some Monday level of difficulty crosswords -these all seem to be Friday standard. An example "Aircraft taken by Lizzie Borden" . Now you might all be thinking ah the axe murderer -chopper obviously but if you have never heard of her, you are a bit stuck. Have to pop out for a while so will pick up answers later.

[Neveracrossword]

1 I think it's just an anagram of Ruminate with the M, motorway, replacing the N, new.

[cashier]

4 Broadcast-sow around Fish-parr

[JJ109]

4 Sow (broadcast) about Parr (young salmon) = sparrow

(but fowl outdated term?)

[ubasses]

2 coomb is a valley remove middle letter.

[Etch]

3. 'Laughing stock' is a reference to the phrase 'love laughs at locksmiths':
https://proverbhunter.com/love-laughs-at-locksmiths/

Found by googling [locksmith laugh]