Call promises of payment untrustworthy (7)
I believe the answer is:
dubious
'untrustworthy' is the definition.
(I've seen this before)
'call promises' is the wordplay.
'call' becomes 'dub' (both can mean to name).
'promises' becomes 'IOUs' (promises to pay a debt).
'dub'+'ious'='DUBIOUS'
'of payment' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for dubious that I've seen before include "Ambiguous or suspect" , "Open to suspicion" , "Doubtful, uncertain" , "Unsure, unconvinced" , "Doubtful, not convinced" .)