Amused by strange need to conceal success (7)
I believe the answer is:
enjoyed
'amused by' is the definition.
(to be amused by something is to enjoy it)
'strange need to conceal success' is the wordplay.
'strange' indicates anagramming the letters.
'to conceal' indicates putting letters inside.
'success' becomes 'joy' (as in the phrase 'any joy?').
'need' with letters rearranged gives 'ened'.
'ened' placed around 'joy' is 'ENJOYED'.
(Other definitions for enjoyed that I've seen before include "Liked" , "Took delight in" , "Took pleasure in" , "Delighted in" , "Derived pleasure from" .)