If most indisposed by the head cold, get sweets (7)

'sweets' is the definition.
(comfit is a kind of sweet)

'if most indisposed by the head cold' is the wordplay.
'indisposed' is an anagram indicator.
'by' says to put letters next to each other.
'the head' says to take the initial letters.
The first letter of 'cold' is 'c'.
'if'+'most'='ifmost'
'ifmost' anagrammed gives 'omfits'.
'omfits' after 'c' is 'COMFITS'.

'get' is the link.