Showing approval on leaving popular musical (6)
I believe the answer is:
liking
'showing approval on leaving' is the definition.
The answer and definition can be both related to thinking as well as being present participle verbs.
Maybe they are linked in a way I don't understand?
'popular musical' is the wordplay.
I cannot quite see how this works, but
'popular' could be 'in' (something that's 'in' is fashionable) and 'in' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for liking that I've seen before include "Being in favour (of)" , "A feeling of regard or fondness" , "Partiality" , "Penchant" , "Fondness (for thing)" .)