Incorporate tricky clue in last bit of crossword (7)
I believe the answer is:
include
'incorporate' is the definition.
(thesaurus)
'tricky clue in last bit of crossword' is the wordplay.
'tricky' indicates anagramming the letters.
'last bit of' indicates one should take the final letters.
The final letter of 'crossword' is 'd'.
'clue'+'in'+'d'='clueind'
'clueind' is an anagram of 'INCLUDE'.
(Other definitions for include that I've seen before include "Allow participation in" , "Comprise; allow to take part" , "Take as part of a group" , "Cover" , "Contain as part of group" .)