Put on endless party for chaps (4)
I believe the answer is:
stag
'party for chaps' is the definition.
'stag' can be an answer for 'party' (I've seen this before). I am not sure about the 'for chaps' bit.
'put on endless' is the wordplay.
'put on' becomes 'stage' (to put on a show is to present or stage it).
'endless' means to remove the last letter.
'stage' with its last letter taken away is 'STAG'.
Can you help me to learn more?
(Other definitions for stag that I've seen before include "Stock Exchange speculator standing" , "This party is for men only" , "American party" , "Game - speculator" , "Stockmarket operator gambling on a quick profit" .)