Regular payments securing a form of support will have you feeling better (7)
I believe the answer is:
happier
'feeling better' is the definition.
'regular payments securing a form of support' is the wordplay.
'regular payments' becomes 'hp' (hire purchase, payment made in instalments).
'securing' indicates putting letters inside.
'form of support' becomes 'pier' (type of support or structure).
'hp' going around 'a' is 'hap'.
'hap'+'pier'='HAPPIER'
'will have you' acts as a link.
(Other definitions for happier that I've seen before include "More joyful" , "More cheerful" , "Gladder" .)