Support Lincoln tipster principally (4)
I believe the answer is:
abet
'support' is the definition.
(thesaurus)
'lincoln tipster principally' is the wordplay.
'lincoln' becomes 'abe'.
'principally' suggests taking the first letters.
The initial letter of 'tipster' is 't'.
'abe'+'t'='ABET'
(Other definitions for abet that I've seen before include "Incite, help" , "Aid (in wrongdoing)" , "Aid and help, perhaps in crime" , "Incite or encourage" , "Criminally endorse" .)