Calling on Conservative behaving very humbly (8)
I believe the answer is:
cringing
'behaving very humbly' is the definition.
(someone might cringe from shame)
'calling on conservative' is the wordplay.
I cannot quite see how this works, but
'calling' could be 'ringing' ('ring' can be a synonym of 'call') and 'ringing' is present in the answer.
'conservative' could be 'c' (UK political abbreviation) and 'c' is found in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for cringing that I've seen before include "Wincing in fear or embarrassment" , "Drawing back in fear or embarrassment" .)