Page badly needing medicine (4)
I believe the answer is:
pill
'medicine' is the definition.
(pill is a kind of medicine)
'page badly' is the wordplay.
'page' becomes 'p'.
'badly' becomes 'ill' ('ill' can be adverbial as in 'ill-advised').
'p'+'ill'='PILL'
'needing' is the link.
(Other definitions for pill that I've seen before include "Dreadful person" , "may be the cure" , "Medicinal pellet" , "Form of medicine" , "Medicinal tablet" .)