I get it: navy mobilised seeing dismal outlook (10)

I believe the answer is:

negativity

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'dismal outlook' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.

'i get it navy mobilised' is the wordplay.
'mobilised' indicates an anagram (I've seen this in other clues).
'i'+'get'+'it'+'navy'='igetitnavy'
'igetitnavy' anagrammed gives 'NEGATIVITY'.

'seeing' is the link.

Can you help me to learn more?

(Another definition for negativity that I've seen is " Expression of pessimism".)

I've seen this clue in The Everyman puzzle in The Observer.

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