Paltry charge regularly billed (6)
I believe the answer is:
feeble
'paltry' is the definition.
(I've seen this before)
'charge regularly billed' is the wordplay.
'charge' becomes 'fee' (fee is a kind of charge).
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
The alternating letters of 'billed' are 'ble'.
'fee'+'ble'='FEEBLE'
(Other definitions for feeble that I've seen before include "Wimpish" , "Weak from illness or age" , "Very weak, infirm" , "Physically weak or lacking effectiveness" , "Weak, frail" .)