I saw this question some time ago, but at the time I took it to be a straightforward question to which I didn't know the answer. BUT I looked at the puzzle for the first time last night and I now think I know where you are coming from! I expect you've already finished it, but just in case, I think the word you are looking for is 'silver'. This pairs up with side & tail.....and tail does double duty with pony. If you want any more help - and in time for tomorrow's post - I shall be dropping in to this site on and off until after midnight and then prob after 10 am tomorrow ( Sunday ). Sorry not to have got back to you before.