Difficult time accepting hard idea (7)
I believe the answer is:
thought
'idea' is the definition.
('thought' can be a synonym of 'idea')
'difficult time accepting hard' is the wordplay.
'difficult' becomes 'tough' ('tough' can be similar in meaning to 'difficult'**).
'time' becomes 't'.
'accepting' means one lot of letters goes inside another.
'hard' becomes 'h'.
'tough'+'t'='tought'
'tought' placed around 'h' is 'THOUGHT'.
(Other definitions for thought that I've seen before include "Orwell's sort of police" , "Mental idea" , "Philosopher must master this" , "Cogitation" , "Idea, opinion" .)