It is in fact a long claw (5)
I believe the answer is:
talon
'claw' is the definition.
(I know that talon is a type of claw)
'it is in fact a long' is the wordplay.
'it is in' indicates the answer is hidden within the clue.
'TALON' can be found hidden inside 'fact a long'.
(Other definitions for talon that I've seen before include "hunting hook" , "Sharp hooked claw" , "ogee moulding" , "One hooked on bird" , "Tonal (anag.)" .)