Most important to be proper, cautious, when wife away? (7)
I believe the answer is:
primary
'most important' is the definition.
(primary means the main or most important)
'proper cautious when wife away?' is the wordplay.
I cannot really see how this works, but
'proper' could be 'prim' (prim and proper) and 'prim' is found in the answer.
'away?' could be 'a' (abbreviation as used in sports fixtures) and 'a' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
'to be' is the link.
Can you help me to learn more?
(Other definitions for primary that I've seen before include "Main" , "Of chief importance" , "Cardinal" , "Principal" , "The colours from which all others can be made" .)