Is enough for decay, getting old, suppressing new (4,2)
I believe the answer is:
runs to
'is enough' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'decay getting old suppressing new' is the wordplay.
I cannot quite understand how this works, but
'old' could be 'o' (common abbreviation eg in OE for Old English) and 'o' is present in the answer.
'new' could be 'n' (common abbreviation eg NT for New Testament) and 'n' is found in the answer.
'decay' could be 'rust' (rusting is a kind of decaying) and 'rust' is found within the leftover letters.
No letters remain.
This explanation may well be incorrect...
'for' is the link.
Can you help me to learn more?