It's rough and could be smoother (9)
I believe the answer is:
sandpaper
'be smoother' is the definition.
(I've seen this before)
'it's rough and' is the wordplay.
I cannot really understand how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is located in the answer.
'it' could be 'sa' (old-fashioned abbreviation for sex appeal) and 'sa' is located in the answer.
This explanation may well be incorrect...
'could' is the link.
Can you help me to learn more?
(Other definitions for sandpaper that I've seen before include "Means of smoothing wood" , "Woodworker's abrasive" , "Abrasive substance" , "Make smoother" , "Abrasive sheet (DIY)" .)