Give thanks at ten, when cover's provided to help one avoid one's duties (3,7)
I believe the answer is:
tax shelter
'cover's provided to help one avoid one's duties' is the definition.
I can't tell whether this defines the answer.
'give thanks at ten when' is the wordplay.
'give' means one lot of letters go next to another.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'at' means one lot of letters go next to another.
'ten' becomes 'X' (Roman numeral).
'when' becomes 'shelter' (I can't justify this - if you can you should believe this answer much more).
'x' put next to 'shelter' is 'xshelter'.
'ta'+'xshelter' is 'TAX SHELTER'.
Can you help me to learn more?
(Another definition for tax shelter that I've seen is " offshore investment, say".)