Bare need to pinch bottom ignored (5)
I believe the answer is:
'ignored' is the definition.
Both the definition and answer are adjectives. Perhaps they are linked in a way I don't understand?
'bare need to pinch bottom' is the wordplay.
I cannot quite see how this works, but
'to' is found in the answer.
The remaining letters 'nic' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for tonic that I've seen before include "medicinal preparation" , "An enlivener" , "Important note" , "something nice and fresh" , "Key" .)