...wanting part to count... (5-4)
I believe the answer is:
third-rate
'wanting' is the definition.
Both the answer and definition are adjectives. Maybe there's a link between them I don't understand?
'part to count' is the wordplay.
'part' becomes 'third' (fraction).
'to count' becomes 'rate' (I've seen this in another clue).
'third'+'rate'='THIRD-RATE'
Can you help me to learn more?
(Other definitions for third-rate that I've seen before include "Very inderior in quality - do a count" , "Very inferior in quality in numeric description" , "Of very poor quality" , "Very inferior in quality, using ordinal number" , "Very inferior in quality - count down" .)