Slips up and gives approval (4)
I believe the answer is:
nods
'slips' is the definition.
(I've seen this in another clue)
'up and gives approval' is the wordplay.
I cannot quite understand how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is found in the answer.
'approval' could be 'od' (OD is an example) and 'od' is found in the answer.
A single letter 's' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for nods that I've seen before include "Non-verbal indications of assent" , "Is careless" , "Shows assent" , "Indicates assent" , "Affirmative gestures" .)