Again I object; phone for corrective (8)
I believe the answer is:
remedial
'corrective' is the definition.
(I've seen this before)
'again i object phone' is the wordplay.
'again' becomes 're' (prefix meaning 'again').
'i object' becomes 'me'.
'phone' becomes 'dial' (dial phone is a kind of phone).
're'+'me'+'dial'='REMEDIAL'
'for' is the link.
(Other definitions for remedial that I've seen before include "appropriate for poor learners" , "Providing a cure or treatment for illness or deficiency" , "palliative" , "Providing cure or help for disability" , "for slow learners" .)