Merely look on as a useful thing to have available (5,2)
I believe the answer is:
stand by
'have available' is the definition.
Although both the answer and definition are verbs in their base form, I don't understand how one could define the other.
'merely look on as a useful thing' is the wordplay.
I cannot really understand how this works, but
'a' could be 'an' and 'an' is present in the answer.
This explanation may well be incorrect...
'to' acts as a link.
Can you help me to learn more?
(Other definitions for stand by that I've seen before include "One ready to step in" , "the kind of passenger that may not get on with others" , "Item or person ready for use in emergency" , "One ready for emergency duty" , "last-minute ticket" .)