WordNet (r) 3.0 (2006):

focus on
    v 1: center upon; "Her entire attention centered on her
         children"; "Our day revolved around our work" [syn: focus
         on, center on, revolve around, revolve about,
         concentrate on, center]

Moby Thesaurus II by Grady Ward, 1.0:

44 Moby Thesaurus words for "focus on":
   act on, act upon, address to, affect, allude to, attend closely to,
   attend to business, be alert, be obsessed with, bring to attention,
   bring to notice, call attention to, cite, concentrate,
   concentrate on, concentrate the mind, concentrate upon,
   direct attention to, direct to, fix on, give heed, influence,
   look lively, look out, look sharp, mention, miss nothing,
   operate on, pay attention, pay heed, pick out, point at, point out,
   point to, refer to, scrutinize, specify, study, take care,
   take heed, touch on, treat, watch out, work on