Husband to rescue (4)
I believe the answer is:
save
This clue is a double definition.
'husband' is the first definition.
(saving is a kind of husbanding)
'rescue' is the second definition.
(saving is a kind of rescuing)
'to' acts as a link.
(Other definitions for save that I've seen before include "Spend less" , "Husband" , "Prepare for a rainy day" , "Bar" , "Apart from" .)