“Pay up without feelings” said Spooner, irritating (10)
I believe the answer is:
nettlesome
'irritating' is the definition.
(synonyms)
'pay up without feelings said spooner' is the wordplay.
I cannot really understand how this works, but
'pay' could be 'nett' (I've seen this before) and 'nett' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for nettlesome that I've seen before include "causing irritation" , "annoying" .)