Observer Everyman Answer And Explain Please!

[Gavmacp]

Two I have not got are..
7d. Fuel's particular job, releasing energy (6). ?E?R??
13a. United in funny old game (4). ??D?
Confirm and explain the following..
21a. Confused amateur's opening with seconds in meal (2,3) at sea but don't quite get.
22d. Residue after street collection (5). Thinking stash St + ash.

[Fibonacci]

13a U + old - Ludo

[scorpiojo]

Pet rol(e)
Ludo - anag U + old
A(mateur) + tea + s(econds)
St(reet) ash(residue)

[Fibonacci]

7d pet rol(e) - petrol

[ubasses]

22 yes St(reet) ash (residue)

[scorpiojo]

At sea = confused

[Lie-in King]

7d Pet-rol(e)
13a Ludo - 'u(nited) (in) anag 'old'
21a At sea - 'a(mateur)' (opening) + 's(econds)' (in) 'tea'
22d Yes, as you have it

[Gavmacp]

Thank you as always! A little easier this week.