Celebrate detailed newspaper (7)
I believe the answer is:
observe
'celebrate' is the definition.
(I know that celebrate can be written as observe)
'detailed newspaper' is the wordplay.
'detailed' means to remove the last letter (the word must be end-less or 'de-tailed').
'newspaper' becomes 'observer' (I've seen this before).
'observer' with its last letter taken off is 'OBSERVE'.
(Other definitions for observe that I've seen before include "Spot, watch" , "Notice, perceive" , "Watch carefully" , "Notice or make a remark" , "Mark" .)