Sailor's mistress, I see, put up with poet (8)
I believe the answer is:
hamilton
'sailor's mistress' is the definition.
'hamilton' can be an answer for 'mistress' (I've seen this before). I'm not certain of the 'sailor's' bit.
'i see put up with poet' is the wordplay.
'i see' becomes 'ah' (exclamation used to indicate understanding).
'put up' is a reversal indicator.
'with' says to put letters next to each other.
'poet' becomes 'milton' (John Milton).
'ah' back-to-front is 'ha'.
'ha'+'milton'='HAMILTON'
Can you help me to learn more?
(Other definitions for hamilton that I've seen before include "Lady . . . . . . . . was Lord Nelson's lover" , "Port in Canada - capital of Bermuda" , "Scottish town" , "Bermudian capital" , "Emma --, Nelson's lover" .)