At last the roses are pruned and one gives one's approval (8)
I believe the answer is:
endorses
'at last the roses are pruned and one gives one's approval' is the definition.
I can't tell whether this definition defines the answer.
'at last the roses are pruned and one gives' is the wordplay.
'at last' becomes 'e' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'are' becomes 'a' (short for 'are', historical unit of measurement).
'pruned' is a deletion indicator.
'one gives' indicates anagramming the letters.
'and' with 'a' taken away is 'nd'.
'roses'+'nd'='rosesnd'
'rosesnd' anagrammed gives 'ndorses'.
'e'+'ndorses'='ENDORSES'
Can you help me to learn more?
(Other definitions for endorses that I've seen before include "'Supports, backs (8)'" , "Approves, supports" , "One dress (anag.)" , "Countersigns, approves" , "Gives support or approval to" .)