Fellow and I preserve treatment for the hands (8)
I believe the answer is:
manicure
'treatment for the hands' is the definition.
(I've seen this before)
'fellow and i preserve' is the wordplay.
'fellow' becomes 'man' (I've seen this before).
'and' means one lot of letters go next to another.
'preserve' becomes 'cure' (curing is a kind of preserving).
'man'+'i'+'cure'='MANICURE'
(Other definitions for manicure that I've seen before include "Care of hands and nails" , "Care of hands and fingernails" , "Cosmetic nail treatment" , "Professional hand treatment" , "Cosmetic care of the hands" .)