Dad right to nurse sick supporter (6)
I believe the answer is:
pillar
'supporter' is the definition.
(I know that pillar is a type of supporter)
'dad right to nurse sick' is the wordplay.
'dad' becomes 'pa' (both can mean one's father).
'right' becomes 'r' (common abbreviation).
'to nurse' means one lot of letters goes inside another.
'sick' becomes 'ill' (similar in meaning).
'pa'+'r'='par'
'par' enclosing 'ill' is 'PILLAR'.
(Other definitions for pillar that I've seen before include "Upright column" , "Architectural support" , "Building support" , "Upright post" , "person providing reliable support" .)