Parrot initially sick needs tablet (4)
I believe the answer is:
pill
'tablet' is the definition.
(I know that tablet can be written as pill)
'parrot initially sick' is the wordplay.
'initially' indicates taking the first letters.
'sick' becomes 'ill' (similar in meaning).
The initial letter of 'parrot' is 'p'.
'p'+'ill'='PILL'
'needs' acts as a link.
(Other definitions for pill that I've seen before include "Dreadful person" , "Dose of medicine" , "Pellet of medicine" , "Medicinal pellet" , "Medical tablet" .)