Poor quality T (5-4)
I believe the answer is:
third-rate
'poor' is the definition.
(I've seen this before)
'quality t' is the wordplay.
I cannot really see how this works, but
'quality' could be 'rate' (I've seen this before) and 'rate' is present in the answer.
't' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for third-rate that I've seen before include "Very inferior in quality - count down" , "Of very poor quality" , "Very inferior in numerical way" , "Very inferior in quality in numeric description" , "Very inderior in quality - do a count" .)