So is in the front again (9)
I believe the answer is:
therefore
'so' is the definition.
(I've seen this before)
'in the front again' is the wordplay.
'in' indicates putting letters inside.
'front' becomes 'fore' (fore is a kind of front**).
'again' becomes 're'.
'the'+'fore'='thefore'
'thefore' going around 're' is 'THEREFORE'.
'is' acts as a link.
(Other definitions for therefore that I've seen before include "In consequence" , "as result" , "Thus" , "It follows" , "has a triangular formation in maths?" .)