Father, always poetical, is more lavish (5)
I believe the answer is:
freer
'poetical is more lavish' is the definition.
I can't tell whether this definition defines the answer.
'father always' is the wordplay.
'father' becomes 'fr' (abbreviation as in a priest's title).
'always' becomes 'eer' (poetic way of saying ever).
'fr'+'eer'='FREER'
Can you help me to learn more?
(Other definitions for freer that I've seen before include "less inhibited" , "Less constrained" , "More at liberty, less restrained" , "Less restricted" .)