Fluid I hand up for French prince (7)
I believe the answer is:
dauphin
'french prince' is the definition.
'dauphin' can be an answer for 'prince' (dauphin is a kind of prince). I'm unsure of the 'french' bit.
'fluid i hand up' is the wordplay.
'fluid' indicates anagramming the letters.
'i'+'hand'+'up'='ihandup'
'ihandup' with letters rearranged gives 'DAUPHIN'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for dauphin that I've seen before include "former royal" , "Eldest son of the French king" , "Heir apparent to the French throne" , "Old prince" , "King of France's heir" .)