Maybe tactician should include second letter (4)
I believe the answer is:
beta
'second letter' is the definition.
(I've seen this in another clue)
'maybe tactician should include' is the wordplay.
'include' says the answer is hidden in the clue.
'BETA' is hidden within 'maybe tactician should'.
(Other definitions for beta that I've seen before include "final test" , "Second highest grade of mark" , "Greek character - not quite top-notch" , "Character between alpha and gamma" , "Second-class" .)