English politician on way to board at Heathrow? (7)

'board at heathrow?' is the definition.
(emplane can mean to get on a plane)

'english politician on way' is the wordplay.
'english' becomes 'e' (abbreviation).
'politician' becomes 'MP' (Member of Parliament).
'on' is a charade indicator (letters next to each other).
'way' becomes 'lane' (lane is a kind of way).
'e'+'mp'+'lane'='EMPLANE'

'to' acts as a link.