Nigel in Reform welcomes unusual form of protection delivering sorrowful lines (9)

'protection delivering sorrowful lines' is the definition.
I can't tell whether this defines the answer.

'nigel in reform welcomes unusual form' is the wordplay.
'in reform' is an anagram indicator (I've seen this in other clues).
'welcomes' means one lot of letters goes inside another (in sense of 'invites in').
'unusual form' becomes 'egis' (I can't justify this - if you can you should give a lot more credence to this answer).
'nigel' with letters rearranged gives 'eling'.
'eling' going around 'egis' is 'ELEGISING'.

'of' is the link.

Can you help me to learn more?