Chap turned back before a place in Cambridgeshire specifically (6)
I believe the answer is:
namely
'specifically' is the definition.
(I've seen this before)
'chap turned back before a place in cambridgeshire' is the wordplay.
'chap' becomes 'man' (chap can mean a man).
'turned back' shows that the letters should be reversed in order.
'before' says to put letters next to each other.
'a place in cambridgeshire' becomes 'ely' (I can't explain this - if you can you should give a lot more credence to this answer).
'man' reversed gives 'nam'.
'nam'+'ely'='NAMELY'
Can you help me to learn more?
(Other definitions for namely that I've seen before include "That is to say, specifically" , "Viz" , "Old especially" , "to wit" , "Videlicet" .)