Guard's company (5)
I believe the answer is:
screw
'guard's' is the definition.
(I've seen this before)
'company' is the wordplay.
I cannot quite understand how this works, but
'company' could be 'crew' (a group of people) and 'crew' is located in the answer.
A single letter 's' 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 screw that I've seen before include "Prison officer - salary" , "shot in pool hall" , "Wage - prison officer" , "13ed fastener" , "Tighten by turning" .)