Soldier's call-up following letter from abroad written by King (7)

I believe the answer is:

pikeman

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'soldier's' is the definition.
(thesaurus)

'call-up following letter from abroad written by king' is the wordplay.
'call-up' becomes 'eman' (I can't justify this - if you can you should give a lot more credence to this answer).
'following' means one lot of letters go next to another.
'letter from abroad' becomes 'pi' (letter of the Greek alphabet).
'written by' says to put letters next to each other.
'king' becomes 'K' (abbreviation for king in chess).
'pi'+'k'='pik'
'eman' after 'pik' is 'PIKEMAN'.

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I've seen this clue in The Independent.

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