Steers line through border regions (5)

'steers' is the definition.
(I've seen this in another clue)

'line through border regions' is the wordplay.
'line' becomes 'el' (el is a kind of line).
'through' means one lot of letters goes inside another (inserted letters go through the word).
'border regions' becomes 'hms' (I can't justify this - if you can you should give a lot more credence to this answer).
'el' put inside 'hms' is 'HELMS'.

Can you help me to learn more?