Entertain sumptuously, giving a chap beer (6)
I believe the answer is:
regale
'entertain sumptuously' is the definition.
(I've seen this in another clue)
'giving a chap beer' is the wordplay.
'giving' says to put letters next to each other.
'a chap' becomes 'reg' ().
'beer' becomes 'ale' (type of beer).
'reg'+'ale' is 'REGALE'.
(Other definitions for regale that I've seen before include "Supply copiously" , "Entertain with stories" , "Entertain with conversation" , "Entertain, delight" , "Entertain royally" .)