Flying Mach One over English Channel, finally seeing The Lizard (9)
I believe the answer is:
chameleon
'the lizard' is the definition.
(chameleon is a kind of lizard)
'flying mach one over english channel finally' is the wordplay.
'flying' indicates anagramming the letters.
'over' is an insertion indicator.
'english' becomes 'e' (abbreviation).
'finally' says to take the final letters.
The last letter of 'channel' is 'l'.
'mach'+'one'='machone'
'machone' with letters rearranged gives 'chameon'.
'e'+'l'='el'
'chameon' placed around 'el' is 'CHAMELEON'.
'seeing' is the link.
(Other definitions for chameleon that I've seen before include "Lizard that can change colour to match surroundings" , "One to blend in" , "Variable-colour reptile" , "Lizard that can adapt its colours to background" , "Lizard hard to spot" .)