Thoughts of some inside a synagogue (5)
I believe the answer is:
ideas
'thoughts' is the definition.
('idea' can be a synonym of 'thought')
'some inside a synagogue' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'IDEAS' can be found hidden inside 'inside a synagogue'.
'of' acts as a link.
(Other definitions for ideas that I've seen before include "Thoughts, concepts" , "Brainwaves" , "Theories" , "Fancies" , "Thoughts or opinions" .)