American poet has penned something to hold up (9)
I believe the answer is:
suspender
'something to hold up' is the definition.
I can't tell whether this defines the answer.
'american poet has penned' is the wordplay.
'american' becomes 'US' (United States).
'poet' becomes 'spender' (Stephen Spender).
'has penned' is an insertion indicator (inserted letters are enclosed or penned in).
'us' put within 'spender' is 'SUSPENDER'.
Can you help me to learn more?
(Other definitions for suspender that I've seen before include "One that supports stocking" , "One responsible for hold-up" , "Supporter" , "hanger on?" , "Stocking-holding strap" .)