Follow right in there to make certain (6)
I believe the answer is:
ensure
'to make certain' is the definition.
('ensure' can be a synonym of 'make certain')
'follow right in' is the wordplay.
'follow' becomes 'ensue' (ensue can mean to follow or happen as a result).
'right' becomes 'r' (common abbreviation).
'in' means one lot of letters goes inside another.
'ensue' enclosing 'r' is 'ENSURE'.
'there' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for ensure that I've seen before include "Make certain, clinch" , "Make certain or safe" , "Guarantee" , "Protect" , "Make certain (something will occur)" .)