Omit a vowel? I'd easily included it (5)
I believe the answer is:
elide
'omit' is the definition.
(I know that elide is a type of omit)
'a vowel? i'd easily included it' is the wordplay.
'a vowel?' becomes 'e'.
'easily' indicates an anagram.
'included' means one lot of letters goes inside another.
'it' becomes 'el' (I can't justify this - if you can you should give a lot more credence to this answer).
'e'+'id'='eid'
'eid' is an anagram of 'ide'.
'ide' going around 'el' is 'ELIDE'.
Can you help me to learn more?
(Other definitions for elide that I've seen before include "Omit (syllable) in speech" , "Cut off" , "Join together, merge" , "Drop off" , "Omit (a sound or syllable) when speaking" .)