Marshall, coach to the West Indies and Hampshire, persuaded McLean to play a season in the county championship after Australian paceman Michael Kasprowicz withdrew from a two-year contract because of heat exhaustion and compatriot Andy Bichel declined the post.
McLean, 24, from St Vincent, has played four Tests and eight one-day internationals and is regarded by Brian Lara as the quickest bowler in the Caribbean. He took five wickets at an average of 40.60 in three Tests against England.
Hampshire head coach Tim Tremlett said: ``Although he would appear to be third- choice, Malcolm rates Nixon very highly indeed.''