Keep leading Tina astray (8)
I believe the answer is:
maintain
'keep' is the definition.
(maintaining is a kind of keeping)
'leading tina astray' is the wordplay.
'leading' becomes 'main'.
'astray' indicates anagramming the letters.
'tina' anagrammed gives 'tain'.
'main'+'tain'='MAINTAIN'
(Other definitions for maintain that I've seen before include "Preserve or insist" , "Uphold, preserve" , "Profess" , "finance" , "Keep going" .)