He should know how to press a suit (8)
I believe the answer is:
advocate
'press a suit' is the definition.
'advocate' can be an answer for 'press' (advocating is a kind of pressing). I'm unsure of the 'a suit' bit.
'he should know how' is the wordplay.
I cannot quite understand how this works, but
'he' could be 'ad' and 'ad' is found within the answer.
This explanation may well be incorrect...
'to' acts as a link.
Can you help me to learn more?
(Other definitions for advocate that I've seen before include "Defender" , "Person who pleads on behalf of another, like barrister" , "Caveat, do about lawyer in court" , "Champion" , "Public supporter" .)