Infection of one's darling — getting one shot (8)
I believe the answer is:
impetigo
'infection' is the definition.
(impetigo is a skin infection)
'one's darling getting one shot' is the wordplay.
'one's' becomes 'I'm' ('one is' is a formal way of saying 'I am').
'darling' becomes 'pet' (both are terms of endearment).
'getting' means one lot of letters go next to another.
'one' becomes 'I' (Roman numeral).
'shot' becomes 'go' (both can mean an attempt).
'im'+'pet'+'i'+'go'='IMPETIGO'
'of' is the link.
(Other definitions for impetigo that I've seen before include "I omit peg to get the childhood skin infection" , "Contagious skin disease causing crusted spots" , "sickness" , "unsightly condition" , "Skin condition" .)