Stretch, almost keep nothing posh over time (3,3)
I believe the answer is:
eke out
'stretch' is the definition.
The definition and answer can be both to do with fundamental existence as well as being verbs in their base form.
Perhaps you can see a link between them that I can't see?
'almost keep nothing posh over time' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'nothing' becomes 'o' (looks like zero - 0).
'posh' becomes 'u' (abbreviation for upper-class - opposite to non-u).
'over' indicates anagramming the letters.
'time' becomes 't' (abbreviation).
'keep' with its last letter taken away is 'kee'.
'kee'+'o'+'u'='keeou'
'keeou' anagrammed gives 'ekeou'.
'ekeou'+'t'='EKE OUT'
Can you help me to learn more?
(Other definitions for eke out that I've seen before include "Make stretch" , "Prolong" , "Make living laboriously" , "Make (meagre supplies) last" , "Economise" .)