Shy company an MP drops out of (3)
I believe the answer is:
coy
'shy' is the definition.
(coy can mean shy or modest)
'company an mp drops out of' is the wordplay.
I cannot quite see how this works, but
'company' could be 'co' (abbreviation) and 'co' is located in the answer.
A single letter 'y' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for coy that I've seen before include "Military team in brief" , "Pretending to be shy or bashful" , "Affectedly modest or shy" , "not forthcoming" , "Reserved" .)