Threaten to imply I had gone inside (10)
I believe the answer is:
intimidate
'threaten' is the definition.
(I've seen this before)
'i had gone inside' is the wordplay.
'i had' becomes 'I'd' (common contraction).
'gone' becomes 'intimate' (I can't justify this - if you can you should give a lot more credence to this answer).
'inside' is an insertion indicator.
'id' inserted into 'intimate' is 'INTIMIDATE'.
'to imply' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for intimidate that I've seen before include "Scare" , "Cow" , "Frighten" , "Threaten" , "Strike fear into" .)