Keep in date somehow (6)
I believe the answer is:
detain
'keep' is the definition.
(I know that keep is a more specific form of detain)
'in date somehow' is the wordplay.
'somehow' indicates anagramming the letters.
'in'+'date'='indate'
'indate' is an anagram of 'DETAIN'.
(Other definitions for detain that I've seen before include "Hang on to" , "Imprison" , "Keep waiting or under restraint" , "Keep in custody or delay" , "Sing to (someone)" .)