Patch up two Royal Engineers? (6)
I believe the answer is:
repair
'patch up' is the definition.
(I've seen this in another clue)
'two royal engineers?' is the wordplay.
I cannot quite see how this works, but
'two' could be 'pair' (pair is a kind of two) and 'pair' is found in the answer.
'royal' could be 'r' (common abbreviation e.g. RM - Royal Marine) and 'r' is found in the answer.
A single letter 'e' remains 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 repair that I've seen before include "darn?" , "Mend, restore to good condition" , "It may be effected by" , "Make good again" , "Mend, put right" .)