Entertained without a thought (5)
I believe the answer is:
mused
'thought' is the definition.
(musing is a kind of thinking)
'entertained without a' is the wordplay.
'entertained' becomes 'amused' (synonyms).
'without' suggests deleting specific letters.
'amused' with 'a' removed is 'MUSED'.
(Other definitions for mused that I've seen before include "Was deep in thought" , "Thought (to oneself)" , "Was absorbed in thought" , "Contemplated" , "'Meditated, mulled (5)'" .)