In Ibiza, agreed to have soft drink (3)
I believe the answer is:
sip
'drink' is the definition.
(sipping is a kind of drinking)
'in ibiza agreed to have soft' is the wordplay.
I cannot quite see how this works, but
'soft' could be 'p' (musical abbreviation for piano, 'soft') and 'p' is found within the answer.
The remaining letters 'si' is a valid word 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 sip that I've seen before include "Small mouthful of fluid" , "Take in slowly" , "Drink slowly" , "Drink, small mouthful" , "Drink in tiny mouthfuls" .)