Work and work to guard against endless excess (10)
I believe the answer is:
oversupply
'excess' is the definition.
(thesaurus)
'work and work to guard against endless' is the wordplay.
I cannot quite see how this works, but
'work' could be 'ply' (I've seen this in other clues) and 'ply' is found within the answer.
'against' could be 'v' (abbreviation for 'versus') and 'v' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for oversupply that I've seen is " Provide with too much".)