Give up some misplaced enthusiasm (4)
I believe the answer is:
cede
'give up' is the definition.
(I know that give up can be written as cede)
'some misplaced enthusiasm' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'CEDE' can be found hidden inside 'misplaced enthusiasm'.
(Other definitions for cede that I've seen before include "Yield formally" , "Surrender or relinquish possession" , "Give up rights or possession" , "Give up (power to another)" , "Relinquish control of" .)