Only takes book to English strait (6)
I believe the answer is:
solent
'strait' is the definition.
(I know that Solent is a strait)
'only takes book' is the wordplay.
'only' becomes 'sole' (synonyms).
'takes' is a charade indicator (letters next to each other).
'book' becomes 'nt' (New Testament).
'sole'+'nt'='SOLENT'
'to english' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for solent that I've seen before include "Channel north of IOW" , "Water to north of IOW" , "Channel N. of IOW" , "The ---, water N. of I. of Wight" , "Channel north of the Isle of Wight" .)