Fizzy drinks help to keep a daughter on the up (5)
I believe the answer is:
sodas
'fizzy drinks' is the definition.
(I've seen this before)
'help to keep a daughter on the up' is the wordplay.
'help' becomes 'sos' (emergency abbreviation SOS).
'to keep' means one lot of letters goes inside another.
'a daughter' becomes 'd'.
'on the up' becomes 'a' (I can't justify this - if you can you should give a lot more credence to this answer).
'd'+'a'='da'
'sos' going around 'da' is 'SODAS'.
Can you help me to learn more?
(Other definitions for sodas that I've seen before include "Fizzy drinks" , "Soft drinks" .)