Popular celebrity pinching pound causes anger (7)
I believe the answer is:
inflame
'anger' is the definition.
(I've seen this before)
'popular celebrity pinching pound' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'celebrity' becomes 'fame' (celebrity can mean the quality of being famous).
'pinching' indicates putting letters inside (taking inside).
'pound' becomes 'L' (the pound sign is based on an L).
'fame' going around 'l' is 'flame'.
'in'+'flame'='INFLAME'
'causes' acts as a link.
(Other definitions for inflame that I've seen before include "Provoke; aggravate" , "Incite" , "Make (a situation) worse" , "Excite passionate feelings" , "Exacerbate" .)